Cloud Hosting or an Apples and Oranges Comparision
Comparing the offering of different cloud computing service providers is pretty much like comparing Apples and Oranges. However on the websites of many cloud hosting providers you do find a feature comparison table (usually against amazon EC2). Not surprisingly EC2 always comes off second best. In spite of that EC2 is still in business which means there is something worth investigating. But first a full disclosure: our company is already using Amazon EC2 and we are happy with it. Our DeadlineDue.com site is hosted on an EC2 instance and also relies on the Amazon Associates API to fetch book information. Other than that there is no other factor influencing the contents of this post.
Comparison between different service providers has been made difficult by the fact that some of them charge you for RAM while other don't. Similarly you may or may not be charged for a virtual hard drive. To make matters worse different providers provide different virtual CPUs sometimes the CPU is described rather vaguely:
"We believe that customers will typically get results similar to a 2ghz processor, but it can vary depending on the applications requirements."
What's that a P4? a Xeon? or perhaps it's a Celeron. It's actually none of those. All the virtual servers have virtual CPUs but it would be nice if the service provider can say something like "EC2 Compute Unit (ECU) – One EC2 Compute Unit (ECU) provides the equivalent CPU capacity of a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor." (< a href="http://aws.amazon.com/ec2/#instance">Amazon) so you know what you are getting into.
The first step in comparing these services would be to normalize them so that we are comparing various citrus fruits rather than apples against oranges. But normalizing the CPU isn't so easy. Most people would tell you that a 2.0GHz Xeon is better than a 2.0GHz Core 2 Duo but by how much? You will not easily find a definitive answer. One reason is that different processors are better for different things. Your Core 2 Duo might even perform better on your desktop when used for gaming.
Because of the lack of scientific data, we are forced to split our applications into two different types - CPU intensive apps and non CPU intensive apps. A Spam filter will likely fall into the former category and a web server delivering mostly static content into the latter. For Non CPU intensive apps we will lump all the Xeons and non Xeons together. For CPU intensive apps we will multiply the processor speed by a factor. In the same manner, we will lump together all the RAM regardless of their nominal speeds. Hard drive speeds will also be different but they will suffer the same fate as the RAM and the CPU
to be continued...